Certain prior art systems may attempt to use global positioning system (GPS) receivers to maintain proper spacing between two vehicles during the unloading or transferring of agricultural material or other material, such as coal and other minerals, between the vehicles. However, such prior art systems are susceptible to misalignment of the proper spacing because of errors or discontinuities in the estimated position of the GPS receivers. For example, one or more of the GPS receivers may misestimate its position because of electromagnetic interference, multipath propagation of the received satellite signals, intermittent reception of the satellite signals or low received signal strength of the satellite signals, among other things. If the vehicles use cameras or other imaging devices in an outdoor work area, such as an agricultural field, the imaging devices may be subject to transitory sunlight, shading, dust, reflections or other lighting conditions that can temporarily disrupt proper operation of the imaging devices; hence, potentially produce errors in estimated ranges to objects observed by the imaging devices. Thus, there is a need for an improved system for managing the unloading of agricultural material from a vehicle to compensate for or address error in the estimated positions or alignment of the vehicles.